Advancing Intervention Science for Probationers with Serious Mental Illnesses This Mentored Research Scientist Development Award (K01) application proposes career development, training, and research activities for candidate Dr. Matthew Epperson. These activities will result in the development and feasibility testing of a novel intervention targeting treatment adherence and criminal risk (TACR) for probationers with serious mental illness (SMI), and advance efficient identification of SMI among probationers. The candidate's long-term career goal is to become a leading expert in the intersection of mental health and criminal justice, with emphasis on developing, implementing, and evaluating interventions for CJ-involved persons with SMI. In order to advance the candidate toward this goal, the following career development objectives are defined in this application: Career Development Objective 1 - INTERVENTION DEVELOPMENT: Increase knowledge and skills necessary to design interventions targeting treatment adherence and criminal risk for persons with SMI. Career Development Objective 2 - INTERVENTION IMPLEMENTATION: Develop expertise in implementation science. Career Development Objective 3 - INTERVENTION EVALUATION: Gain proficiency in advanced research design, methodology, and statistics for intervention research. Key elements of the research career development plan include mentoring by a team of experts, including: Dr. Deborah Gorman-Smith, Dr. Robert Drake, Dr. Faye Taxman, Dr. Robert Gibbons, and Dr. Curtis McMillen. Additionally, the candidate will complete specific coursework and training in evidence-based approaches to treatment adherence and criminal risk, interventions for SMI, research in criminal justice settings, conducting randomized trials, implementation science, and statistical methods, including training in computerized adaptive testing of SMI symptoms. The research project involves the development, refinement, and pilot testing of the TACR intervention. Through in-depth interviews with probationers with SMI and focus groups with probation officers and staff, the TACR intervention will be assessed for acceptability and feasibility. The project will result in a feasibility pilot testing of the TAR intervention with 48 probationers with SMI (24 in the TACR group and 24 in the control group) to further assess feasibility of intervention delivery, as well as preliminary outcomes. Aims for the project are: AIM 1: Develop and refine a manualized, novel intervention, delivered by probation officers, targeting treatment adherence and criminal risk (TACR), for probationers with SMI. AIM 2: Examine the feasibility and acceptability of TACR intervention delivery through pilot testing in a specialized probation setting, and assess preliminary outcomes. AIM 3: Identify innovative applications of computer adaptive SMI measurement methodology to advance intervention research on SMI in the criminal justice system. Career development and research activities will lead to a R01 application at the end of the award period, which will entail an efficacy trial of the TACR intervention for probationers with SMI. The training plan, paired with my unique combination of extensive clinical experience and research training, will position me to become a leading expert in the intersection of mental health and criminal justice, with emphasis on developing, implementing, and evaluating interventions for justice-involved persons with SMI.